In a communications network, a delay is a key performance indicator (KPI), and also affects use experience of users. With development of communications protocols, a scheduling interval of a physical layer that affects a delay most obviously is also increasingly small. A scheduling interval is 10 ms in initial Wideband Code Division Multiple Access (WCDMA), a scheduling interval is shortened to 2 ms in High-Speed Packet Access (HSPA), and a scheduling interval is shortened to 1 ms in Long Term Evolution (LTE).
Due to a small-delay service requirement, a short transmission time interval (TTI) frame structure needs to be introduced in an LTE physical layer, so as to further shorten a scheduling interval, and a TTI may be shortened from 1 ms to a value between 1 symbol (symbol) to 0.5 ms. The aforementioned symbol may be an orthogonal frequency division multiplexing (OFDM) symbol in an LTE system.
FIG. 1 is a diagram of an round-trip time (RTT) delay of data transmission of a base station. As shown in FIG. 1, based on a hybrid automatic repeat request (HARQ) technology, if the base station transmits data to user equipment in a TTI that is numbered i in a downlink (DL) link, and if the user equipment correctly demodulates and decodes the received data, the user equipment feeds back an acknowledgement (ACK) to the base station in a TTI that is numbered i+4 in an uplink (uplink) link. If the user equipment has not correctly demodulated or decoded the received data, the user equipment feeds back a negative acknowledgement (NACK) to the base station in the TTI that is numbered i+4, and the base station determines, based on the ACK or NACK received in the TTI that is numbered i+4, to perform initial data transmission or data retransmission processing in a TTI that is numbered i+8 in the downlink link. The ACK or NACK that is fed back may also be collectively referred to as HARQ-ACK information. In the prior art, lengths of TTIs for transmission in both the uplink link and the downlink link are 1 ms. If a short TTI transmission technology is introduced, for example, when the lengths of the TTIs for transmission in the uplink link and the downlink link are shortened to 0.5 ms or one or more symbols, it may be considered that a processing time is reduced in equal proportion, and the foregoing RTT delay also applies.
LTE supports a carrier aggregation technology, that is, the base station configures a plurality of carriers for one UE to improve a data rate of the UE. The UE supporting the carrier aggregation technology may simultaneously detect downlink data on a plurality of downlink carriers, and the UE needs to simultaneously make a HARQ feedback mechanism for the downlink data on the plurality of downlink carriers. Therefore, it requires that one channel can support transmission of HARQ-ACK information of the downlink data on the plurality of downlink carriers. In addition, to enable the base station to schedule the UE and transmit the downlink data on the plurality of downlink carriers, the UE needs to feed back channel state information CSI (Channel State Information) on the carriers to the base station. In a particular uplink TTI, the UE may need to simultaneously feed back HARQ-ACK feedback information for downlink scheduling data and the CSI information on the plurality of carriers to the base station. The UE may further send scheduling request (SR) information to the base station, to request an uplink UL-SCH resource from the base station.
When the UE supports receiving data on a plurality of downlink carriers of different TTI lengths, the UE may need to feed back HARQ-ACK feedback information for downlink scheduling data and the CSI information on the plurality of carriers to the base station in a particular uplink TTI. Because TTI lengths on different downlink carriers are different, delays corresponding to a HARQ-ACK feedback time sequence and a CSI feedback time sequence on different downlink carriers may be different, and consequently the UE may need to transmit HARQ-ACK information and CSI information that correspond to different downlink TTI lengths in the particular uplink TTI. Using the HARQ-ACK feedback time sequence as an example, FIG. 2 is a diagram of an RTT delay of data transmission corresponding to carriers of different TTI lengths. As shown in FIG. 2, FIG. 2 includes one uplink carrier (component carrier, CC for short) and two downlink carriers, and the two downlink carriers are respectively a downlink carrier 1 and a downlink carrier 2. A time length of a TTI of the downlink carrier 1 is equal to that of the uplink carrier, and a time length of a TTI of the downlink carrier 2 is not equal to that of the downlink carrier 1. If a base station sends data in a TTI that is numbered i+2 and that is of the downlink carrier 1, after receiving the data, UE feeds back uplink control information in a TTI that is numbered i+6 and that is of the uplink carrier. If the base station sends data in a TTI that is numbered i and that is of the downlink carrier 2, after receiving the data, the UE feeds back uplink control information at a moment corresponding to a TTI that is numbered i+4 and that is of the downlink carrier 2, that is, in the TTI that is numbered i+6 and that is of the uplink carrier. That is, a feedback conflict of HARQ-ACK information may occur in the TTI that is numbered i+6 and that is of the uplink carrier.
In the prior art, there has been no processing method for transmitting uplink control information when there are a plurality of pieces of uplink control information corresponding to time domain resources of different lengths and a conflict occurs between the time domain resources corresponding to the plurality of pieces of uplink control information.